Method for frequency transposition in a hearing device and a hearing device

Abstract

The present invention is related to a method for frequency transposition in a hearing device by transforming an acoustical signal into an electrical signal (s) and by transforming the electrical signal from time domain into frequency domain to obtain a spectrum (S). According the present invention, a frequency transposition is being applied to the spectrum (S) in order to obtain a transposed spectrum (S′), whereby the frequency transposition is being defined by a nonlinear frequency transposition function, Thereby, it is possible to transpose lower frequencies almost linearly, while higher frequencies are transposed more strongly. As a result thereof, harmonic relationships are not distorted in the lower frequency range, and at the same time, higher frequencies can be moved into a lower frequency range, namely in an audible range of the hearing impaired. The transposition scheme can be applied to the complete signal spectrum without the need for switching between non-transposition and transposition processing for different parts of the signal. Therefore, no artifacts due to switching are encountered when applying the present invention.

1 . Method for frequency transposition in a hearing device by 
 transforming an acoustical signal into an electrical signal (s) and    transforming the electrical signal (s) from time domain into frequency domain to obtain a spectrum (S),    characterized in that    a frequency transposition is being applied to the spectrum (S) in order to obtain a transposed spectrum (S′),    whereby the frequency transposition is being defined by a nonlinear frequency transposition function.    
     
     
         2 . Method according to  claim 1 , characterized in that the nonlinear frequency transposition function is perception-based.  
     
     
         3 . Method according to  claim 1  or  2 , characterized in that the nonlinear frequency transposition function is a continuous function.  
     
     
         4 . Method according to  claim 2  or  3 , characterized in that the perception-based frequency transposition function is being defined by one of the following functions: 
 Bark function;  
 ERB function; or  
 SPINC function.  
 
     
     
         5 . Method according to one of the  claims 1  to  4 , characterized in that the frequency transposition function is being defined in a look-up table.  
     
     
         6 . Method according to one of the  claims 1  to  5 , characterized in that the transposed spectrum (S′) is being applied to an output transducer ( 7 ).  
     
     
         7 . Hearing device comprising 
 at least one microphone ( 1 ),    a transformation unit ( 3 ) and    a signal processing unit ( 4 ),    whereas the transformation unit ( 3 ) is operationally connected to the at least one microphone ( 1 ) and to the signal processing unit ( 4 ),    characterized in that a nonlinear transposition function is applied in the signal processing unit ( 4 ).    
     
     
         8 . Hearing device according to  claim 7 , characterized in that the nonlinear frequency transposition function is perception-based.  
     
     
         9 . Hearing device according to  claim 7  or  8 , characterized in that the nonlinear frequency transposition function is a continuous function.  
     
     
         10 . Hearing device according to  claim 8  or  9 , characterized in that the perception-based frequency transposition function is defined by one of the following functions: 
 Bark function; or  
 ERB function; or  
 SPINC function.  
 
     
     
         11 . Hearing device according to one of the  claims 7  to  10 , characterized in that a look-up table is provided in which the frequency transposition function is defined, the look-up table being either operationally connected to the signal processing unit ( 4 ) or being integrated into the signal processing unit ( 4 ).  
     
     
         12 . Hearing device according to one of the  claims 7  to  11 , characterized in that at least one output transducer ( 7 ) is operationally connected to the signal processing unit ( 4 ).  
     
     
         13 . Hearing device according to one of the  claims 7  to  11 , characterized in that an inverse transformation unit ( 5 ) or any other synthesizing means are operationally connected to the signal processing unit ( 4 ).  
     
     
         14 . Hearing device according to  claim 13 , characterized in that at least one output transducer ( 7 ) is operationally connected to the inverse transformation unit ( 5 ) or to the other synthesizing means.  
     
     
         15 . Use of the method according to one of the  claims 1  to  6  for a binaural hearing device.